The present invention relates to an electrical connection device between a handle and a steering column in a steering apparatus for a vehicle.
Recently, in connection with a progress of electronic control for an automobile, various kinds of switches have been provided in the handle, which may be called "a steering wheel", in the steering apparatus for the automobile. Accordingly, there is a need for connecting these switches with electric cables on the steering column side by means of wiring. Since the handle for the vehicle is constructed so as to rotate in both the clockwise and counter-clockwise directions with several revolutions, a flexible flat cable (FFC) having a plurality of lead wires is generally used in an electrical connection device between the handle and the steering column. In the electrical connection device, the flexible flat cable is arranged between a rotor fixed to a handle axle and a housing fixed to the steering column, in either spiral wound condition or a "reversed" spiral wound condition such that the cable is turned up on the half way.
Generally, the electrical connection device includes a cylindrical rotor to which a handle axle of the automobile is fixed and a housing which is fixed to the steering column to rotatably support the rotor at an outside portion thereof. The rotor consists of a first rotor element and a second rotor element to be assembled into the first rotor element from its axial direction. On the other hand, the housing consists of an upper cover and an undercover, both of which define an annular space for accommodating the above-mentioned FFC.
In the assembled state, an axial upper end of the first rotor element is brought into contact with the inner surface of the upper cover. The first rotor element is provided at the axial upper end with a projection projecting toward the inner surface of the upper cover. Opposing the projection, the upper cover is provided with two parallel projections projecting toward the first rotor element, which define a groove therebetween. In assembly, the projection of the first rotor element is engaged into the groove, so that a displacement of the first rotor element in the radial direction can be reduced with respect to the upper cover.
On the other hand, the second rotor element is provided with a flange which extends radially outward of the second rotor element. The flange has a projection formed at its tip to come into contact with the bottom surface of the undercover, so that the second rotor element is engaged with undercover.
In the above-mentioned electrical connection device, in order to facilitate the assembling operation, the projection of the first rotor element is adapted so as to engage into the groove by enough clearance and furthermore, a clearance is also formed between the outer periphery of the second rotor element and the inner periphery of the undercover.
Therefore, when the first and second rotor elements rotate together with an operation of the handle and particularly, when the rotating direction of the rotor is reversed, the rotor would be subject to a force for urging it to move radially with respect to the housing. Consequently, the projection of the first rotor element is brought into contact with respective side surfaces of the projections by planes and similarly, the outer periphery of the second rotor element is also brought into contact with the inner periphery of the undercover by plane, so that the contact-noise is produced thereby to reduce the reliability of the device.
In order to restrict an occurrence of the contact-noise, there may be proposed an electrical connection device in which the first and second rotor elements are urged to the upper cover and the undercover, respectively, by an urging means such as springs. In this case, however, a level of sliding-noise caused by the rotor's rotation on the housing would be increased because the pressure between the rotor and the housing is increased, so that the above problem would still remain.